Switching apparatus and system



March 13, 1928.

J. L. REYNOLDS SWITCHING APPARATUS AND SYSTEM Filed April 1. 1927 n AAAA Inventor ttorney ment for controlling the speed of the motor- Patented ivi ar. s, 1928.

UNITED STATES PATENT- OFFICE- p,

JOHN LOUIS REYNOLDS, OF LONG ISLAND CITY, NEW YORK, ASSIGNOR, BY MESNE AS- SIGNMENT S, TO ELECTRICAL RESEARCH PRODUCTS INC., A CORPORATION OF DELA- wean.

Application filed April 1,

This invention relates to switching systems, and with particularity to the automatic connection of sound transmitters with a sound reproducerf The invention is in the nature of an improvement upon the switching arrangement disclosed in my copending application Serial No. 180,323, filed April 1, 1927. Inapplication Serial No. 180,323, thereis disclosed a synchronized sound and picture projecting system wherein anelectrical netof the program.

It is one of the principal objects of the invention therefore to automatically cut out a transmitter when the speed of an associated driving motor begins to vary.

A feature of the invention is in the com: bination of motor-driven sound translating devices associated with each other and with a common sound reproducer through an electrical network, together with a switch automatically operated to effectively cut out a translating device when the associated motor is not running at the required speed.

In synchronized sound and picture systems where the sound record is embodied in a separate medium "from that of the picture film, for example, in a wax record, it is essential that the sound record driving motor be driven at a fixed and uniform speed. This is particularly important when succes sive sound records are to be reproduced, in

order that no change in pitch may occur from one record to another. However, at times it may be desirable to operate the picture projector alone, and at a different speed from that fixed for a synchronized program.

' Accordingly, it is a feature of the invention to provide a switch and circuit arrangewhich drives a picture projector and sound 'ing it.

-SWITCHING} APPARATUS AND SYSTEM.

1927. Serial No. 180,326.

reproducer, whereby, with the switch in one position, the speed of the driving motor is fixed atthe proper value, while in another position of the switch the operator is enabled to vary the speed of the driving apparatus.

Other features and advantages inherent in the invention will be revealed by a consideration of the descriptions given herein after and as specifically pointed out in the appended claims.

For this purpose the inventionis shown and described in itsrelation to a sound translating and reproducing system, but it is understood that the inventive idea is capable of application to other types of sound transmission systems, as will be apparent to those familiar with the art to which the invention relates. Furthermore, only such parts of a sound reproducing system are illustrated in the drawing as are considered necessary to obtain a complete understanding of the invention and one preferred mode of employ- Figdl shows schematically a control system. embodying my invention while Fig. 2 is a characteristic curve of the system.

Referring to the drawing, there is shown in the upper left portion thereof a picture projectingmachine of known construction P and a phonograph turntable 25 carrying 'a disc sound record 16, boththe projector and the turntable being driven through suitable gearing from the motor M which has an auxiliary field winding 1. Motor M may be of any suitable type whose speed can be controlled by the strength of the current through the auxiliary field winding. In the drawing, an alternating current motor is shown, the armatureof which receives current from the alternating current source 3 when switch-S is operated either to the right or to the left. Motor M drives a small gen:

erator G which delivers alternating current to the input circuit of the three-element vacuum tube T whose output circuit includes a marginal relay 4, and the field wind ing 1. 'VVhile a separate battery 28 is shown for supplying the plate potentialfor tube T it is obvious that extra windings may be placed on generator G fo'r supplying both the plate potential and filament currents. The input'circuit of the tube T comprises the inductance L and either the variable condenser 5 or the fixed condenser 6, depend ing upon whether switch S is in its left or right-hand position. Included in the input circuit of tube '1, is the grid polarizing battery 7 which is normally adjusted so that when motor M, is operating at the required speed. for a synchronized picture and sound program, the current in the output circuit is sufiicient to operate relay 4. It is to be noted that for such a r ogram, switch S is operated to its right-liand position with the fixed condenser 6 connected in the input circuit of the tube T Condenser 6 and inductance L are of such values that the current flowing in the plate circuit of the tube is sufficient to operate relay 4, this current remaining constant so long as motor M is rotating at the proper speed required for a synchronized program. Fig. 2 illustrates the manner 111 which the current through auxiliary field 1 varies with the frequency ot the currents from generator G and consequently in accordance with changes in the motor speed. The curve of Fig. 2 corresponds to the resonance curve of the tuned circuit including the condenser 5, or condenser t3, and the inductance'L The values of inductance and capacity 6 are preferably so chosen that when the motor M is rotating at the proper speed required for a synchronized sound and moving picture program, the current in the output clrcuit of tube T, andthe field wind ing 1 has the value P. Should, therefore, for any reason, motor M slow down, the frequency of the currents applied to the input circuit of tube T, will be lowered, resulting, in an increase of current through the field 1, and a corresponding increase of the motor speed. Should motor M tend to increase its speed, the field current becomes less and the motor steadies down to the required speed. When it is desired to use the picture projector P independently of the sound reproducing apparatus, it may be convenient to operate the said projector at a different speed from that set by the inductanceL, and condenser 6. For this purpose the switch S, is operated to its left-hand position, causing the fixed condenser- 6 to be replaced by the variable condenser 5, the operator is now enabled to vary the speed of motor M sirnpl by adjusting the condenser 5, which varies t e working point on the resonance curve and the strength of the field current.

Assuming that a synchronized sound and moving picture program is to be reproduced and that the. first part of the program is carried by the record 16, and a succeeding part by the record 17 the attendant operates switch S to its right-hand position, completing a circuit for the lamp 8 which remains lighted as a continuous signal, which may be seen from a distance, that the apparatus is operating at the speed required for a synchronized program. Plugs l9 and 20 having been previously inserted in jacks 21 and 23, the artificial line AL is connected at one end to the phonograph reproducing equipment R,, and at the other end to the reproducing apparatus R It is to be noted that the apparatus shown in the lower lefthand portion of Fig. 1 is similar to that shown in the upper right-hand portion and further description thereof at this point is believed to be unnecessary.

It is desirable that the sound projecting apparatus represented scheimltically by the loud siealtcr 12 be disconnected while the motor 1L is changing speed. This change of speed may be unavoidable as, for example, during the very short interval that the motor requires to come up to full speed, or because of failure of the power supply to operate the motor within the required speed limits. For this purpose relays 4 and Qikare provided. As hereinbct'ore described, relay 4 is marginal and only receives suflicient current to be operated, when the motor M, is rotating at the speed required for a synchronized program. \Vhilc the motor is coming up to speed, the current in the plate circuit of tube T, is insufiicient to operate relay 4, and a circuit is completed from ground through the winding of relay 22, sleeve of jack 21, sleeve of plug 19, contacts of relay 4, contacts 33 and 34 of switch S1, to battery and ground. Relay 22 is operated. over this circuit and maintains a short-circuit around the electromechanical translator 15 while the motor M is changing speed, thus preventing any gradual changes of pitch in the loudspeaker 19, which would occur if device 15 were not short-circuited.

then the turntable 25 has attained the proper speed, as fixed by condenser 6 and inductance L marginal relay 4 operates and relay 22 releases to remove the short circuit from the device 15 which is actuated by the stylus 14 following the sound groove in the disc 10. Device 15, therefore, generates sound modulated currents corresponding to the varying amplitudes of the groove and feeds these currents into the artificial line AL. The operator then adjusts the contacts 35 and 36 to include a greater or less number of sections of the line AL in circuit with the translator 15 and the input circuit of the electron discharge amplifier A whose output circuit is connected to the loudspeaker 19.. The points at which the contacts 23, 24 are to be set to give the proper volume of sound in the loudspeaker 12 may be determined in advance of the starting of motor M in which case the setting of these contacts may be accomplished while the motor is attaining speed or at any previous time.

When the end of the reel in the picture projector P and the end of the cutting-in isc 16, are about to be reached, the attendant opens switch S and operates switch lUD S to the right. Motor'M then starts to -fslow down and motor M comes up to speed. While mowrM is slowing down, the current in the output circuit of tube T is diminishing, relay 4 releases and relay 22 operates,-

thus preventing the device 15 from affecting the loudspeaker 12. Similarly, while motor M is changing speed, relay 26 is normal and relay 24 operates to closethe circuit of relay 22 which maintains a short circuit around the device 27; While the switchover from motor M to motor M is being effected theiattendant moves contacts 35 and 3.6 downwardly to a predetermined point beyond the electrical midsection of the line AL, thus decreasing the number of sections of the line AL in,

circuit with device 27 and. the amplifier A and allowing the reproducer R to take control of the'loudspeaker 1 2. I

If itis desired to blend the soundmodulated currents from translator 15 into those from the translator 27, the attend ant allows the motor M to remain running when the end ofthe record in disc 16 is about to be reached and starts the motor M Consequently relay 4 remains operated and device 15 continues tofeed currents into the line AL' until the actual end of the record is reached. Just prior to the end of the record in disc lfi'being" reached, the attend-.

ant moves contacts 35 and 36 downwardly to a predetermined point beyond the center of the line AL. The line AL may be SO proportioned that with the contacts 35, 36 in the center of the-line, the effect of either device .15 or- 27 upon the loudspeaker 12 is substantially zero. As the contacts. 35, 36 move beyond the midpoint of the line AL, the currents from device 27 increase in strength and reproducer R takes control. Contacts 35, 36 may'form part of a rotary switch such as disclosed in m application Serial No. 180,323, led April 1',

1927 in which event the movement of these contacts may be madealinost instantaneously and without the switchoverv from device '15 to device 27 being noticeable to an auditor.

For a detailed description ofthe manner in which the artificial line AL functions to control the switchover and blending eifects, reference may be had to my copending applicat-ion Ser1al No.- 180,323, hereinbefore re ferred to.

Should it be desired to operate the picture projecting-machine and sound reproducing apparatus synchonously at a d'ifierent peed from that set by :condenserfi, switches S and S5 are operated to the left and the variable condensers adjusted to the point corresponding to the desired speed. Under these circumstances switches 31 and 32 are opened that relays i and 26 maybe ineffective to cause short-circuitingof the line AL as here-- inabove described. e I

,It is obvious that the invention, while such a reproducin iphotoelectric cell to the line AD, 7 vacuum tubes, in order to render copending shown in connection with -a reproducing system employing wax records may also be used in systems employing photographic records, in which case, if the sound record is on the same film as the motion picture, the turntable 25 is not required. In this case the-reproducer is replaced by a photoelectric cell which-is'excited in accordance with the varying transparencies of. the photographic sound record. It is also desirable in system to couple the output of the by means 0 the variations in the photoelectric current most eiiective. It is also clear that the soundrecord may beon a distinct film from the motion picture, in which case the'turntable is replacedby a picture projector,

for the sound record. Absolute synchronism between the photographic? sound record and the motion pictureisassured because of the mechanical connection between the respective driving shafts.

While in the foregoing description and in the drawing specific apparatus is disclosed,.

it is understood that the invention is not to be limited thereto.' For exam le, the driv ing motors M -M may be irect current motors instead of the alternating current type, and devices 15, 27 may take the formof any other known apparatus for electroinagnetically translating sound variations into corresponding electric currents. 'It is also within the scope'of the invention to use a a single motor for driving both turntables and both picture projectors, in which case a *the respective turntables and projectors.

2. In combination, a sound translating" mechanism comprising a rotatable element-- and an electrical pick-up device, a sound reproducer associated with said device, a motor for driving said element, switching means responding to changes in speed of said motor, said switching means effective to electrically disassociate said pick-up-device" from said reproducer when said motor is changing speed.

lay res'ponsive only when said motor is run-. ning at a definite speed, a device for trans-. lating a sound record into current impulses, said device having a member 'driven from saidmotor, a sound reproducer. to be oper- 3. In combinatioma driving motor,-are-- &

ated by said current impulses, and means controlled by said relay for short-circuiting said translating device. i

4. In combination, a plurality of devices for" generating sound modulated currents, each device comprising a rotatable member, means for drivin each of said rotatable men1bers, a netwoi lr with which said devices are associated, a reproducer also associated with said network, means for progressively varying the point of association of said .reproducer with said network to effectively switch said reproducer from one to the other of said devices, and automatically operated means for short-circuiting said other device when the associated driving means is varying in speed,

5. In combination, a plurality of devices for generatin sound modulated currents, a network to w iich said currents may be applied simultaneously, a reproducing device associated with said network,-means for adjusting the point of association of said'reproducer with said network to effectively switch the control of said reprodueer from one to the other of said devices, and a relay for cutting. off electricall' said other device from the reproducer until said other device is generating the sound modulated currents "at the proper general pitch.

6. In combination, a plurality of mechanical media sound records, means for driving each of said records, a device associated with each record for producing correspondingly modulated currents, a sound reproducer, means for switching said reproducer from one to the other of said devices without interruption, and automatic means for short-' circuiting said other device until the associated driving means has reached a required,

8. In combination, a plurality of devices.

for translating a record of sound variations into corresponding'current variations, each device comprising a driven element, a motor for driving said element, a non-adjustable tuned circuit for controlling the speed of said motor, an adjustable tuned circuit for varying the speed of said motor, a repreducer operated by said impulses, a switch for associating either of said circuits with said motor, means ei fective when said non-tuned circuit is associated with said motor for cut ting out said reproducer when said motor varies in speed, and means for rendering said last mentioned means ineffective when said tuned circuit is associated with said motor.

9. In combination a sound translating device, driving means for said device, a second reproducing device operated under control of said translating device, means for regulating the speed of said driving means comprising an electron dischar e device having its input controlled by sai driving means, the output of said discharge device in turn controlling the speed of said driving means, and means controlled b the output of said discharge device to ren er said transmitting device ineffective to control said reproducer while the speed of driving means is varying.

10. In combination a sound translating mechanism comprising a driven element, an

electrical pickup device, means for driving said element, means for controlling the speed of said driving means, an electron discharge device having its input circuit controlled by said driving means, the output of said discharge device in turn controlling said speed controlling means, a non-adjustable tuned circuit associable with the input of said discharge device, an adjustable tuned circuit associable with the input of said discharge device, a switch adapted in one position to associate said non-adjustable circuit with said device and in another position to-associate'saidatljustable circuit with said device,

and visual indicating means adapted to be permanently operable so long as said nonadjustahle circuit is associated with said device.

11. In combination an electromagnetic sound reproducer, a motion picture projecting mechanism, means efiective when a synohronized sound and picture program is to be reproduced for driving said 'reprodncer and said .picture mechanism .at predetermined speed ratios, means for'rendering said sound repruducer ineffective when said ratio is departed'irom, means .for changing said ratio without rendering said sound reproducer ineffective, andfa visual signal permanently lighted so ion as saidipredetermined ratio isnot departed om.

In testimony whereof, I' have signed my name ito this specification, this l-8th day of March 1927. I

J. Louis anvuoiins, 

